Cyanuric acid or stabilizer is a chemical that is manually added to salt water pools to protect the chlorine from the direct rays of the sun. Maintaining cyanuric acid levels around 60 ppm – 80 ppm is recommended for salt water pools and it might need to be higher if you receive significant sun.
Cyanuric acid is added to swimming pools to increase the lifespan of chlorine and minimize chlorine requirements. Referred to commercially as pool stabilizer, it acts as an invisible shield and is especially important for salt water pools since the chlorine that is produced by a salt chlorinator is unstabilized.
Is cyanuric acid necessary in a saltwater pool?
Cyanuric acid is required to protect the chlorine that your salt chlorinator produces as well as chemical chlorine that you may add to your pool. Chlorine is very susceptible to the UV rays of the sun and studies have shown that chlorine can be reduced by up to 90% with just two hours of direct sunlight.
So not only is chlorine used to kill contaminants in the water, it also has to deal with the UV rays of the sun which help to burn it off. By using stabilizer, you are helping to extend the life of chlorine in your pool and possibly minimize the work needed to keep water chemistry in check.
Chlorine in a pool is classified in several ways:
Free chlorine: The amount of chlorine in a pool at a specific time that is active and waiting to be used to sanitize the pool’s contaminants. Free chlorine is unattached to contaminants and is able to sanitize them when required.
Combined chlorine: The amount of chlorine that has already attached itself to contaminants. It is thus combined with contaminants and is no longer usable.
Total chlorine: The sum of free chlorine and combined chlorine.
For pool owners, you can get test strips that measure free chlorine since it’s the one you’re most interested in ie. how much chlorine is freely available to sanitize the pool water?
How to add cyanuric acid to a saltwater pool
Cyanuric acid (CYA) in the form of commercial pool stabilizer is sold in buckets of powder and is typically sprinkled slowly into the pool. You may also find a liquid product that can be poured into the pool, typically in the skimmer.
Follow the instructions carefully because some stabilizer can coagulate and clog pump systems if added too quickly. Slowly sprinkling powder in the side skimmer with the pump running or placing the powdered stabilizer in a skimmer sock to slowly dissolve in the water is another common method.
Pool stabilizers often take up to 2 days to fully dissolve and it isn’t uncommon to see bits of the stabilizer shooting out of the return jets as you’re sprinkling it in the skimmer.
Some chemical chlorine products such as chlorine pucks or crystal chlorine that is made specifically for pool usage has stabilizer added. So when you use these products to shock your salt water pool you’re already adding in stabilizer too.
But since a salt water pool’s chlorine production comes predominantly from the chlorinator and is thus unstabilized, manually adding stabilizer to the water is required to help extend the life of the chlorine.
How often do you add cyanuric acid to a saltwater pool?
In a salt water pool, the normal recommended level of stabilizer is 60 ppm – 80 ppm. In a regular chlorine pool, the ideal range is lower at 30 ppm – 50 ppm.
The reason why you want a higher level of stabilizer in a salt water pool is because your chlorinator is manufacturing chlorine on an ongoing basis according to the setting you have chosen. It helps your pool build up chlorine residual faster if the chlorine is being protected with the stabilizer since it’s better protected from UV rays.
But a higher stabilizer level also requires a higher level of free chlorine since the higher the stabilizer level, the less effective your chlorine!
Check your chosen product instructions but a typical dosage is 1 pound of stabilizer for every 3,000 gallons of water but it also depends on what your current stabilizer reading is i.e. how low it is.
How do I lower the cyanuric acid level in my saltwater pool?
When your stabilizer level is too low, you run the risk of requiring more chlorine which increases your costs and makes your salt chlorinator work harder. When your stabilizer level is too high, it can overpower the chlorine and reduce its effectiveness to sanitize the water.
The only way you can quickly lower the cyanuric acid level of your pool is to drain water and then refill the pool with fresh water (i.e. from your garden hose) to dilute the stabilizer levels.
Of course, you also run the risk of lowering other aspects of water chemistry such as chlorine and salt if you have to drain significant water.
How soon can I swim in my pool after adding cyanuric acid?
In general terms, you are normally requested to wait until 20 minutes after adding a chemical to a pool with the pump running before swimming.
Check the label of the product for more information but once the product is in the water, you normally only need to wait 20 minutes before swimming again.
There is nothing stopping you from adding chemicals to your pool at dusk when swimming is over for the day too. Then the chemical(s) can filter through the system overnight with the pump running and you can swim again the next day.